Electromagnetic construction



June 27, 1939. 5 QSTLER Q 2,164,041

ELECTROUAGNETI C CONSTRUCTION Original Filed May 31, 1934 2 Sheets-Sheet l June 27, 1939. E. s. OSTLER 2,164,041

ELECTROMAGNETIC CONSTRUCTION I Original Filed May 31, 1934 2 Sheets-Sheet 2 Patented June 27, 1939 PATENT OFFICE ELECTROMAGNETIC CONSTRUCTION Ernest S. Ostler, Park Ridge, Ill., assignor, by mesne assignments, to General Time Instruments Corporation, ration of Delaware New York, N. Y., a corpo- Application May 31, 1934, Serial No. 728,370 Renewed November 16, 1934 3 Claims.

My invention relates to an electromagnetic construction.

One of the objects of my invention is to provide an improved electromagnetic actuator which will be quiet in operation.

A further object is to provide such an actuator in which very little force is required to restore the armature, thus enabling the use of a relatively light restoring or operating spring.

A further object is to provide an improved electromagnetic actuator in which the armature moves transversely of the magnetic field and which avoids the use of pins or shafts as a support for the armature.

A further object is to provide an improved electromagnetic actuator having a double magnetic field produced by a single coil.

Further objects and advantages of the invention will be apparent from the description and 20 claims.

In the drawings, in which two embodiments of my invention are shown:

Figure 1 is a plan view of part of an electric time stamp head, including an electromagnetic actuator for the type Wheels;

Fig. 2 is a side elevation of Fig. 1;

Fig. 3 is a side elevation of the electromagnetic actuator and associated parts;

Fig. 4 is an axial sectional view of the electromagnetic actuator;

Fig. 5 is a detail view showing the manner in which the armature rocks;

Fig. 6 is a diagrammatic view showing the pole piece and armature in position;

Fig. '7 is a side View of Fig. 6;

Fig. 8 is a side elevational view of a somewhat difierent form of actuator; and

Fig. 9 is a detail sectional view showing the pivotal mounting for the armature of Fig. 8.

Referring to the drawings in detail, and first to Figs. 1 to 7, inclusive, the construction shown comprises a part of an electric time stamp head comprising a pair of side plates I secured together in a suitable manner and pivotally mounted to rock about an axis at 2, type wheels 3 mounted on the front end of said stamp head, an electromagnetic actuator 4 mounted on the rear end of said stamp head, and transmission from the electromagnetic actuator to the type wheels whereby each actuation of the electromagnetic actuator will cause a one-step movement of the initial one of the type wheels.

The electromagnetic actuator comprises a single coil 5, a three-armed pole piece 6, and a twoarmed armature l, rockably mounted with respect to the pole piece to move in a plane transverse to the magnetic field. The coil 5 surrounds the central arm 8 of the pole piece and the two side arms 9 of the pole piece extend up alongside and embrace the coil. This arrangement creates two magnetic fields, as indicated by the arrows in Figs. 6 and '7. All three of the arms of the pole piece serve as poles, the polarity of the two outside poles being opposite to that of the central pole. These pole pieces, in cooperation with the rockable armature, provide two magnetic field, as shown in Fig. 6. When in its fully actuated position (shown in full lines in Fig. '7), the left hand lower edges of the armature legs [0 come into contact with the upper left hand edges of the arms 9 of the pole piece to eliminate the air gap between the armature and pole piece at the contacting surfaces, thus completing the magnetic path. When the armature, rocks back to its retracted position (shown in dotted lines in Fig. 7), the lower edges of the legs 10 of the rocking armature move out of contact with the upper edges of the arms 9 of the pole pieces, thus breaking the magnetic path. The desired rocking movement of the armature, with respect to the pole pieces, is accomplished by the provision of two supporting plates ll-one on each of the side arms 9 of the pole piece on which the lower ends of the legs I 0 of the rocking armature rest. These supporting plates may be of bronze or any suitable non-magnetic material and may be secured to the side arms of the pole piece in any suitable manner, as by the screws l2 which also serve to secure the pole piece to the side plates l of the stamp head.

The upper edge of each of these supporting plates is notched out to provide upwardly-extending projections 13 between which the lower end of one of the legs I!) of the rocking armature is received and by which it is positioned. The rocking armature is held in assembled operative relation with respect to the pole piece by means of a pair of screws l4 threaded into the sides of the rocking armature and freely movable in slots 15 in the side plates I of the stamp head. The upper edge 15 of each supporting plate constitutes a plane bearing surface and is inclined slightly with respect to the upper edge of the side arm to which it is secured, as shown in Fig. 5. The lower edge of the leg of the armature which bears on the upper edge of this supporting plate may be curved slightly to provide a rocking or rolling movement on this inclined edge l6 of the supporting plate so that as the armature is rocked from the dotted-line to the full-line position shown in Fig. 7, it will have a rocking downhill movement, gradually lessening the air gap between the lower left-hand edge of the leg of the armature and the upper left-hand edge of the pole piece until, in its fully actuated position, the lower left-hand edge of the leg of the armature is in contact with the upper left-hand edge of the side arm of the pole piece, thus completely eliminating the air gap between the contacting surfaces of the armature legs and the side arms so as substantially to reduce the reluctance of the magnetic circuit independently of the air gap between the central arm of the pole piece and the adjacent portion of the armature.

The transmission from the rocking armature'to the initial type wheel comprises a rock lever ll, carrying at its left-hand end a pawl l8 which. operates a ratchet wheel 19 rotatable with the initial type wheel. This rock lever is'secured to an oscillatable rock plate 25) pivotally mounted at 2|, which rock plate has a down-turned lip 22 which is engaged by an actuating finger 23 secured to the upper end of the rocking armature.

When the electromagnet is energized, the armature moves from the position shown in Fig. 3 to the position shown in Fig. 4, causing the lower 'end1ofthe'rock plate 20 to move to the left and raise the end of=the rock lever I! which carries the pawl 18 which actuates the type wheels.

-movement of the armature is cushioned by means of a leaf spring 2l having-its central portion secured at 28 to a U-shaped bracket 29 mounted on the side plates l of the stamp head. The free ends of this'leaf spring engage the upper end of the rocking armature and cushion its return movement. 'Ihe'adjacent portion of the central arm-of the polepiece and of-the rocking armature are curved, asshownatfiil in Fig. 4, to provide for the rocking -movement of the armature and to maintain the adjacent portions of the armature and'the central arm of the pole piece in close proximity'to each other during this rocking movement.

- The :curve 'of the convex upper face of thecentral arm of the-polepiece is struck from apoint 38 somewhat to the left of the left edge line of the central arm with a relatively long radius,

while the curve of the concave lower face of the adjacent portion of the armature isstruckfrom a point 30 onthe left edge line of the armature arm with a somewhat shorter radius. Thus the outeredges of the armature face are closer to the pole face than the central portion when the armature is in operated position. As the armature moves to its unoperated position, the left edge of the armature face moves farther away from the pole so that in unoperated position, the

distance between the pole and the left handedge of the armature face is greater than the distance between the armature face and the right edge of the pole face. The curvatures of the two surfaces, as noted above, together with the slightly downhill rocking movement of the armature on its supports as it operates, produces a movement which swings the armature face to a position over the pole face and at the same time moves the two surfaces closer together. There is little tendency for the armature to swing past its operated position as this would reduce the cross-sectional area of the direct field between the two surfaces. and would also move the surfaces farther apart since the armature would then tip up on the left hand edge of its side arms at the points of support.

The movement of the armature, as outlined above, greatly increases the magnetic attraction between the two surfaces as the armature nears its operated position, the attraction or force varymg as the square of the distance between the two surfaces. Thus, the important and desirable ac- "tion of the ordinary magnet which brings two .surfaces toward each other as the magnet operates is retained, and at the same time the objectionable click or noise occasioned by the contacting of the two surfaces of the ordinary magnet is entirely eliminated.

It will benoted that the point of contact between the actuator finger 23 and the downfinger and the down-turned lip.

The construction shown in Figs. 8 and 9 is similar to that just described, except that in this form the armature 1 is mounted to rock about a fixed pivot 3! instead of rocking on the edge of a supporting plate. held inoperative relation with respect to the pole piece, by means ofa retaining washer 32 having an annular flange engaging in arcuate grooves in the pole piece and armature, respectively.

Further modifications will be apparent to those skilled in the art and it isdesired, therefore, that my invention-be limited only by the prior art and the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by'Letters Patent is:

1. In a magnetically operated structure, a magnet having a pole face, an armature adapted to move in a plane substantially parallel to the plane of said pole face supported on side members which form parallel branches for the magnetic field, and means for providing gaps of substantial size. extending completely across the magnetic paths at the points-of support of said armature when the armatureis in unoperated position and for closing the magnetic paths at said points of support when said armature moves to its operated position.

2. In a'magnetically operated structure, a magnet, two side members extending upward from the base of said magnet, apiece of non-magnetic material at the'upper end of each side member having a sloping surface and secured to the side member so "that the u per edge of the sloping surface extends slightly above the upper surface of the side member, an armature for said magnet, and two side arms extending from said armature and v resting on said non-magnetic pieces when said armature is in unoperated position, one

edge jof each side arm adapted to contact one edge of the associated side member when said armature is operated.

V 3. In a magnetically operated structure, a magnet, two side members extending upward from the base of said magnet, an armature for said magnet having two side arms adapted to rest on said two members, respectively, whereby said armature may be moved transversely of said therebetween whensaid'armature-is rocked to its operated position;

' ERNEST S. OS'IIER.

In this form, the armature is 

